This invention relates to a multilayered thermoplastic film, useful as signage films, and to a sign cutting method using the foregoing multilayered film.
Sign cutting methods wherein an image is cut from a polymer film adhered to a pressure sensitive adhesive composite and then transferred to a desired substrate are known. This technique is used to provide a wide variety of signage applications including exterior identification signs as well as decorative or commercial graphics on trucks, cars, boats, and the like. The polymer film that is typically used with these graphic applications is a calendered or dispersion cast polyvinyl chloride (PVC) monolayer film. While the use of these PVC films have met with success in the marketplace, they have also been found to be not entirely acceptable. Neither the PVC films nor the processes for making such films are environmentally friendly. Many of the PVC films employ plasticizers that migrate into the adhesive and degrade the functionality of the adhesive composite. Plasticizer migration is also considered to be related to objectionable spotty film appearance, sometimes referred to as mottle. This problem is especially troublesome in warm weather climates. Many of the processes for making the PVC films are costly. The present invention, which relates to a novel multilayered film structure and to a sign cutting method using the same, overcomes these problems.
U.S. Pat. No. 4,946,532 discloses composite facestocks and liners made of multilayer polymeric films. The multilayer film is comprised of a coextrudate containing a core or base layer and skin layers overlying each side of the core layer. The core layer contains a filler material.
U.S. Pat. No. 5,435,963 discloses an oriented polymeric in-mold label film that includes a hot-stretched, annealed, linerless self-wound film lamina. The film is disclosed as having a face layer for printing, a central layer, and a base layer which includes a heat-activatable adhesive. The working examples disclose a label film with the face layer disclosed as being a mixture of an ethylene/vinyl acetate copolymer and a polypropylene homopolymer. The central layer is disclosed as being a mixture of an ethylene/vinyl acetate copolymer, either polypropylene homopolymer or a random polypropylene copolymer, and optionally a titanium dioxide concentrate. The base layer is disclosed as being a mixture of an ethylene/vinyl acetate copolymer, either a polypropylene homopolymer or a low density polyethylene, and optionally a heat-activatable adhesive and an antistat.
This invention relates to a multilayer film, comprising: at least one polyolefin core layer having a first side and a second side, at least one abrasion resistant first thermoplastic skin layer overlying the first side of the core layer, and at least one second thermoplastic skin layer overlying the second side of the core layer; wherein the composition of the core layer is different than the composition of the skin layers, and the core layer and the skin layers are characterized by the absence of PVC.
In one aspect, the invention relates to a multilayered thermoplastic film, comprising: a thermoplastic core layer having a first side and a second side, the core layer comprising: a polyolefin having a density in the range of about 0.89 to about 0.97 grams per cubic centimeter; and a light stabilizer; at least one abrasion and scuff resistant clear first thermoplastic skin layer on one first side of the core layer, the at least one first skin layer comprising a light stabilizer; and at least one second thermoplastic skin layer on an opposed second side of the core layer, the at least one second skin layer comprising a light stabilizer; the composition of the core layer being different than the composition of the skin layers, the core layer and the skin layers being characterized by the absence of polyvinyl chloride (PVC).
One preferred embodiment of this invention relates to a multilayered thermoplastic film having a blended core composition, comprising: a thermoplastic core layer comprising: a polyolefin having a density in the range of about 0.89 to about 0.97 grams per cubic centimeter and a second polymeric material selected from the group consisting of ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, ionomers derived from sodium, lithium or zinc and an ethylene/methacrylic acid copolymer, and a combination thereof, and a light stabilizer at a concentration of about 1,000 to about 10,000 ppm based on the weight of the core layer.
The invention also relates to a sign cutting method, comprising: providing a pressure sensitive adhesive composite, the composite comprising the foregoing multilayered thermoplastic film, a layer of a pressure sensitive adhesive and a release liner; cutting an image in the multilayered thermoplastic film; and transferring the image to a substrate.